1. Field of the Invention
Fabric-conditioning has taken on increasing importance with increased use of synthetic fibers in articles of clothing. Such synthetic fabrics are initially treated with conditioning agents by the manufacturers, but washing or dry cleaning the fabrics tends to remove the conditioning agents.
Various methods have been proposed to apply conditioning agents to fabrics to improve their various properties. Such fabric conditioners include softeners, antistats, lubricants, bacteriostats, mildew-proofers, moth-proofers and the like. The methods of application include treatment of the fabrics by padding, dipping, spraying and rinsing with liquid solutions of the conditioning agents.
After several washings, clothes made from synthetic fibers tend to have a net surface charge and exhibit annoying tendencies to attract lint and to cling to the wearer. Certain cationic softeners are used on such fibers to provide a softer "hand" to the fabric to neutralize the excess charge, and to thereby eliminate static cling and lint pick-up by clothes made from synthetic fibers.
Until recently, the most typical domestic method of applying fabric softeners to clothing has been by adding the softening agent to the final rinse in the automatic clothes washing machine. This method is inconvenient because the operator must be at the washing machine at the proper time, unless the machine is equipped with an automatic dispenser for the rinse cycle.
The inconvenience of adding fabric softeners at the rinse cycle has generated interest in fabric-conditioning products which may be added to the clothes dryer to tumble with, and condition the drying clothes. Applying fabric softeners in the dryer offers an important convenience because the softeners can be added at the time the clothes dryer is loaded. In addition, the softeners can be applied directly from a solid substrate in solid form, as contrasted with the dilute solutions used in the final rinse cycle of the clothes washing process.
2. Prior Art
Dryer-administered fabric softeners are disclosed in U.S. Pat. Nos. 3,442,692; 3,686,025; 3,895,128; 3,944,694; 3,967,008 and others. Commercially available fabric softener articles include one which comprises a slitted, non-woven substrate carrying a fabric softener, and a second type which is a polyurethane sponge carrying a fabric softener. A third type, which has been marketed to a somewhat lesser extent, comprises a fabric bag containing powdered fabric softeners. The bag containing the softeners is taped, or otherwise secured, to a leading surface on a dryer drum vane. The softener is said to release from the bag and transfer to clothes tumbled in the dryer over a number of dryer loads.
None of the above patents or the commercially available articles include a multiple-layer substrate which can be modified by the dryer operator to expose additional fabric softener for transfer to the tumbling clothes. U.S. Pat. No. 3,944,694 discloses a non-woven substrate provided with slit openings to allow air to pass through the substrate even when it becomes positioned over the dryer vent, but it does not describe multiple-layered substrates for controlled release of fabric softener.
The non-woven substrates described in U.S. Pat. Nos. 3,686,025 and 3,944,694 employ approximately 30% by weight adhesive, based on the total weight of the non-woven substrate, to bind the substrate together. In contrast, the adhesive in the substrate of the present invention comprises about 50% of the total weight of the substrate. Because of the method of manufacture, the substrate of the subject invention tends to have a greater concentration of adhesive on one surface.